Tobacco use, primarily cigarette smoking, is responsible for almost half a million preventable deaths in the United States (US) each year, and the vast majority of new smokers are under the legal age to purchase cigarettes. Cigarette smoking rates are also highest among low socio-economic status (SES) populations (including low-education and low-income groups). In 2009, the U.S. Food and Drug Administration (FDA) was granted regulatory authority over the manufacture, marketing, and distribution of tobacco products in order to protect public health. In March, 2013, the U.S. government decided not to pursue a Supreme Court hearing that may have reversed earlier court decisions ruling that a set of package warning labels proposed by the FDA were unconstitutional. The FDA will now revisit the content of the labels to convey the risks of smoking while maintaining the First Amendment rights to commercial speech of the tobacco companies. This project will examine how variations of FDA-regulated antismoking messages can be most effective for priority populations (youth and low SES groups) by testing message strategies that will cue effectiveness and reduce resistance, while maintaining compliance with the First Amendment. Youth and low SES populations are particularly susceptible to attending to and processing contextual elements of a message that can distract from the central anti-tobacco arguments. These contextual elements, such as color, placement, size, and emotional cues, have been the focus of ongoing policy regulation and legal argument. The proposed research will be continually responsive to newly proposed FDA anti-tobacco messaging and subsequent legal arguments. To accomplish these aims we will conduct 7 controlled laboratory experiments with random assignment of participants to conditions and based on methods applied in several previously published studies. We will conduct research with a total of 3,840 participants by traveling in a mobile laboratory to empirically identified locations where vulnerable populations reside. The mobile experiment lab will allow the team to quickly evaluate newly proposed messages and alternative messages with vulnerable populations that have been traditionally hard to reach while biologically confirming smoking status. This project brings together an interdisciplinary team of researchers from communication, population health, Constitutional law, and public policy and will yield findings that can be immediately applied to FDA policy actions and address legal arguments regarding constitutionality.